1. Field of the Invention
The present invention relates to systems and methods for delivering drugs to a patient. In particular, the present invention relates to systems and methods for subcutaneous infusion of drugs or substances and using energy sources to improve effectiveness of the infused drugs.
2. Background of the Invention
Diabetes is a very serious illness affecting millions of people today. Many diabetic patients require injection of insulin to maintain proper levels of glucose in their blood in order to survive. Such injections of insulin are done using drug delivery systems.
Many medical treatment systems and methods involve drug delivery systems that employ subcutaneous infusions of therapeutic fluids, drugs, proteins, and other compounds. Such delivery systems and methods, especially in the area of insulin delivery, have made use of subcutaneous catheters and continuous subcutaneous insulin infusion (CSII) pumps. In conventional insulin pumps, the pump is configured to be attached to a disposable thin plastic tube or a catheter through which insulin passes into the tissue. The catheter can be inserted transcutaneously, typically on the patient's abdomen and is changed every two to three days. New types of insulin pumps, such as the OmniPod pump manufactured by Insulet Corporation, do not have an external catheter and, instead, a catheter port that is embedded into the pump mechanism.
In many instances, the patients require insulin delivery around the clock to keep proper levels of glucose in their blood. Insulin can be delivered at a basal rate or in bolus doses. The basal rate represents insulin that is continuously delivered to the patient. Such continuous delivery of insulin keeps patient's blood glucose in the desired range between meals and over night. The bolus dose is an amount of insulin delivered to the patient matching a dose of carbohydrates consumed by the patient. When patient consumes food, his or her levels of glucose rise. Some conventional pump mechanisms are configured to react upon command, or by way of an algorithm, to the increase in glucose levels by delivering a bolus dose of insulin that matches the rise in the level of glucose and prevents large glucose excursions. However, many conventional subcutaneous drug delivery systems are incapable of quickly matching or preventing the rise of blood glucose. The delay in such matching is also true in case of the “rapid-acting” insulin. Some of the reasons for this delay include a lag in the absorption of insulin from the injection site and the time it takes for complex insulin molecules to break down into monomers.
Additionally, since blood glucose levels rise immediately following the meal, the delay in matching insulin to the rising levels causes post prandial hyperglycemic events (i.e., when levels of blood glucose are above normal) to occur. Further, occasionally after a certain period of time passes (e.g., 2-3 hours) after a meal, the blood glucose levels drop yet insulin concentrations in the blood rise followed by the peak of the systemic insulin effect and result in causing hypoglycemic events (i.e., when levels of blood glucose are below normal) to occur. Both hyperglycemic and hypoglycemic events are highly undesirable. Additionally, since the local blood perfusion at the insulin infusion region has large variations depending on the ambient temperature and other parameters, it induces large variations to said delay of the peak of time profile of the insulin action. Those variations in the insulin peak action period further increase the variability in the blood glucose level.
Thus, it is desirable to provide a system and a method that provides efficient and timely delivery of the drug to the patient. In particular, it is desirable to provide a system and a method for delivering insulin to the patient that improves effectiveness of insulin in the blood to maintain normal levels of blood glucose and prevent or reduce hyperglycemic and hypoglycemic events.